Belief in the Prophets (PBUT) of God who excel all other persons for whom they are sent for.
All prophets of Allah are perfect and sinless (ma'soom). Prophet Muhammad Mustafa (PBUH&HF) is the last of the prophets sent by God and the sealer of prophets for NO more are to come, EVER!
The total number of prophets (PBUT) that were sent by God to mankind is 124,000 and every nation on earth was given guidance through them.
In fact, all major religions today on earth can be traced to have these divinely guided teachers as their original propagators of the Truth of Allah.
The best of His messengers all came from the same tree i.e. family lineage and many of them are mentioned in the Holy Qur'an which describes who they were and what their mission on earth was.
It is important to note that no prophet on earth ever negated or rejected any of the other divinely ordained prophets and thus their message was always the same and one in purpose.
Each established the law of the One and Only God and showed the way of life for humans to observe. From the very first creation of mankind, there was always a prophet on earth which was Prophet Adam (PBUH). This guidance from the Merciful Allah to establish His complete laws continued to the last Prophet Muhammad (PBUH&HF) who exemplified the letters of the law in his most perfect behavior.
He completed and perfected the one and only True religion, Islam. With the revelation of the last Holy Book, the Qur'an, which is the most protected and perfect book of God with us, he established as part of his mission, every concievable and practical law for mankind to follow in order to attain spiritual perfection.
Great prophets such as Nuh (Noah), Ibrahim (Abraham), Ismail (Ishmael), Ishaaq (Isaac), Yaqoob (Jacob), Yusuf (Joseph), Dawood (David), Sulaiman (Solomon), Musa (Moses), Yahya (John), and Isa (Jesus), - (Peace be upon them all) - all came from the one blessed lineage of Prophet Adam (PBUH) and ended with the last Messenger, Muhammad (PBUH&HF).
It is also important to note that anyone who ascribes imperfections or mistakes to these divinely guided personalities is ascribing it directly to Allah who is certainly free from such. Acceptance of such ideas is also rejection of the message of Allah entirely.
Thus with prophethood, a believer has to accept in their complete message without any reservations of possible errors or mistakes.